In recent years, an increase in the ingestion of food with high cholesterol has caused a serious increase in adult diseases such as arteriosclerosis and hypertension due to hypercholesterolemia. Under such circumstances, it is strongly sought to develop food with low cholesterol. In particular, with regard to animal fats and oils such as butter or eggs, which are pointed out as high-cholesterol foods, it is desired to remove cholesterol contained therein.
As methods therefor, in recent years, methods in which inclusion compounds with cholesterol are formed using various types of CD, in particular, .beta.-CD composed of 7 molecules of glucose, in order to remove cholesterol from the foods are proposed, and have been already put into practical use (see Japanese Patent Applications Laid-open No. 63-41595, No. 3-14896, No. 3-49647, No. 3-130039, No. 4-93399 and No. 4-229158, WO91-16824, and U.S. Pat. No. 5,063,077).
These methods have made it easy to produce low-cholesterol foods. However, there is almost no report on methods by which CD is recovered in a good efficiency from inclusion compounds of CD with cholesterol and other lipids, obtained as by-products.
Accordingly, a method in which an aqueous suspension of such inclusion compounds is heated to dissociate them into CD, and cholesterol and other lipids, followed by centrifugal separation to recover the respective components has been hitherto employed for the sake of convenience (Japanese Patent Application Laid-open No. 3-14896).
In order to recover CD in a higher purity, a method is also proposed in which a mixture of the inclusion compounds of CD with cholesterol and other lipids is treated with an organic solvent, such as alcohol or hexane, to make cholesterol and other lipids soluble so that they can be recovered (Japanese Patent Application Laid-open No. 4-229158 and W091-16824).
However, in the method in which an aqueous suspension of the inclusion compounds is heated and thereafter centrifuged, it is difficult to sort and recover the respective components, and about 5 to 10% (w/w) of cholesterol or lipids remain in the CD thus recovered. Hence, it has been impossible for the CD recovered, not only to be reused for the removal of cholesterol, but also to be used for other general purposes.
The method in which a mixture of the inclusion compounds is treated with an organic solvent requires the organic solvent in a large quantity, reaction equipment of an explosion-proof type and a solvent recovery apparatus of a large scale. This method can not be said to be economical.